Chapter 31 Mental Disorders Steven Hyman, Dan Chisholm, Ronald Kessler, Vikram Patel, and Harvey Whiteford Mental disorders are diseases that affect cognition, emotion, Twin studies make it clear that environmental risk factors and behavioral control and substantially interfere both with the also play an important role in mental disorders; concordance for ability of children to learn and with the ability of adults to disease among identical twins, although substantially higher function in their families, at work, and in the broader society. than among nonidentical twins, is still well below 100 percent Mental disorders tend to begin early in life and often run a (Kendler and others 2003). However, as is the case for genetic chronic recurrent course. They are common in all countries factors, investigation of environmental risk factors has proved where their prevalence has been examined. Because of the difficult. For schizophrenia, where nongenetic components of combination of high prevalence, early onset, persistence, and risk may include obstetrical complications and season of birth impairment, mental disorders make a major contribution to (Mortensen and others 1999), perhaps as a proxy for infections total disease burden. Although most of the burden attributable early in life, research has been hampered by the modest proven to mental disorders is disability related, premature mortality, effect of the nongenetic risk factors identified to date. For especially from suicide, is not insignificant. Table 31.1 summa- depression, anxiety, and substance use disorders, where envi- rizes discounted disability-adjusted life years (DALYs) for ronmental risk factors are more robust, adverse circumstances selected psychiatric conditions in 2001. associated with risk, such as early childhood abuse, violence, Mental disorders have complex etiologies that involve inter- poverty, and stress (Patel and Kleinman 2003) correlate with actions among multiple genetic and nongenetic risk factors. multiple disorders and could be affected by selection bias as well Gender is related to risk in many cases: males have higher rates as by bias associated with self-reporting.Generalizable,prospec- of attention deficit hyperactivity disorder, autism, and sub- tive cross-cultural studies are needed to delineate nongenetic stance use disorders; females have higher rates of major depres- risk factors more clearly. Posttraumatic stress disorder (PTSD) sive disorder, most anxiety disorders, and eating disorders. is the mental disorder for which clear environmental triggers are Biochemical and morphological abnormalities of the brain best documented. Even here, though, enormous interindividual associated with schizophrenia, autism, mood, and anxiety dis- variability occurs in the threshold of stress severity associated orders are being identified using approaches such as post- with PTSD as well as in the evidence from twin studies of genetic mortem analysis and noninvasive neuroimaging. Major world- influences on stress reactivity in triggering PTSD. wide efforts under way to identify risk-conferring genes for The last half of the 20th century saw enormous progress in mental disorders are proving challenging, but initial results are the development of treatments for mental disorders. Beginning promising. Identifying the gene or genes causing or creating in the early 1950s, effective psychotropic drugs were discovered vulnerability for a disorder should help us understand what that treated the symptoms of schizophrenia, bipolar disorder, goes wrong in the brain to produce mental illness and should major depression, anxiety disorders, obsessive-compulsive have a clinical effect by contributing to improved diagnostics disorder, attention deficit hyperactivity disorder, and others. and therapeutics (Hyman 2000). The safety and efficacy of antipsychotic, mood-stabilizing, 605 Table 31.1 Disease Burden of Selected Major Psychiatric Disorders, by World Bank Region World Bank region Sub-Saharan Latin America and Middle East and Europe and East Asia and High-income Africa the Caribbean North Africa Central Asia South Asia the Pacific countries World Total population (millions) 668 526 310 477 1,388 1,851 929 6,159 Total disease burden 344,754 104,287 65,570 116,502 408,655 346,941 149,161 1,535,870 (thousands of DALYs) Total neuropsychiatric 15,151 18,781 8,310 14,106 37,734 42,992 31,230 168,304 disease burden (thousands of DALYs) Total burden (thousands of discounted DALYs per year) Schizophrenia 1,146 1,078 696 778 2,896 3,934 1,115 11,643 Bipolar disorder 1,204 883 567 668 2,237 3,118 1,056 9,733 Depression 3,275 5,219 2,027 4,268 14,582 14,054 8,408 51,833 Panic disorder 519 409 264 340 1,081 1,401 536 4,550 Total burden (DALYs per year per 1 million population) Schizophrenia 1,716 2,049 2,247 1,630 2,087 2,126 1,201 1,894 Bipolar disorder 1,803 1,678 1,830 1,400 1,612 1,685 1,137 1,583 Depression 4,905 9,919 6,544 8,944 10,507 7,594 9,054 8,431 Panic disorder 777 777 852 713 779 757 577 740 Percentage of total disease burden Schizophrenia 0.33 1.03 1.06 0.67 0.71 1.13 0.75 0.76 Bipolar disorder 0.35 0.85 0.86 0.57 0.55 0.90 0.71 0.63 Depression 0.95 5.00 3.09 3.66 3.57 4.05 5.64 3.37 Panic disorder 0.15 0.39 0.40 0.29 0.26 0.40 0.36 0.30 Percentage of neuropsychiatric disease burden Schizophrenia 7.56 5.74 8.38 5.52 7.67 9.15 3.57 6.92 Bipolar disorder 7.95 4.70 6.82 4.74 5.93 7.25 3.38 5.78 Depression 21.62 27.79 24.39 30.26 38.64 32.69 26.92 30.80 Panic disorder 3.43 2.18 3.18 2.41 2.86 3.26 1.72 2.70 Source: WHO Global Burden of Disease 2001 estimates recalculated by World Bank region (http://www.fic.nih.gov/dcpp/gbd.html). antidepressant, anxiolytic, and stimulant drugs have been edge exists to guide treatment. It is particularly unfortunate, established through a large number of randomized clinical therefore, that timely diagnoses and the application of trials. Psychosocial treatments have been developed and tested research-based treatments significantly lag behind the state of using modern methodologies. Brief, symptom-focused psy- knowledge in industrial and developing countries alike. As a chotherapies such as cognitive-behavioral therapies have been result, substantial opportunities exist to decrease the enormous shown to be efficacious for panic disorder, phobias, obsessive- burden attributable to mental disorders worldwide by closing compulsive disorder, and major depression. the gap between what we know and what we do. There is, however, an important caveat about the current Mental disorders are stigmatized in many countries and knowledge base for treatment. As is the case for almost all of cultures (Weiss and others 2001). Stigma has been facilitated medicine, randomized clinical trials have been performed by the slow emergence of convincing scientific explanations for largely with highly selected populations in specialized research the etiologies of mental disorders and by the mistaken belief settings in industrial countries. A need exists to subject existing that symptoms are caused by a lack of will power or reflect some treatments to effectiveness trials in more representative popu- moral taint. Recent scientific findings combined with educa- lations and diverse settings, especially in developing countries. tional efforts in some countries have begun to reduce the stigma That limitation notwithstanding, a substantial body of knowl- (Rahman and others 1998), but shame and fear associated with 606 | Disease Control Priorities in Developing Countries | Steven Hyman, Dan Chisholm, Ronald Kessler, and others mental illness remain substantial obstacles to help seeking, to fixed false beliefs that are not explained by the person’s culture diagnosis, and to treatment worldwide. The stigmatization of and that the patient holds despite all reasonable evidence to the mental illness has resulted in disparities, compared with other contrary. illnesses, in the availability of care, in research, and in abuses of Patients also exhibit negative symptoms—that is, deficits in the human rights of people with these disorders. normal capacities, such as marked social deficits, impoverish- This chapter focuses on the attributable and avoidable ment of thought and speech, blunting of emotional responses, burden of four leading contributors to mental ill health globally: and lack of motivation. Additionally, patients typically have schizophrenia and related nonaffective psychoses, bipolar cognitive symptoms, such as disorganized or illogical thinking affective disorder (manic-depressive illness), major depressive and an inability to hold goal information in mind to make disorder, and panic disorder. The choice of these disorders is decisions or plan actions. determined not only by their contribution to disease burden, but also by the availability of data for the cost-effectiveness Natural History and Course analyses. Even where such data are available, they are often from Schizophrenia, as defined in current diagnostic manuals, is industrial countries and extrapolation has been necessary. The almost certainly heterogeneous, but still does not comprise all exclusion of other mental disorders, such as childhood disor- nonaffective psychoses (NAPs). In addition to schizophrenia, ders, from analysis is not because the authors consider these dis- NAPs include schizophreniform disorder,characterized by schiz- orders unimportant but because of the paucity of data.Also, this ophrenia-like symptoms of inadequate duration to qualify as chapter does not specifically deal with the important issue of schizophrenia. Because they cannot be readily disentangled in suicide. A background paper on suicide in developing countries community epidemiological surveys, schizophrenia and other has been developed as part of the Disease Control Priorities NAPs are considered together.Because of the data available,how- Project (DCPP) and is available (Vijayakumar, Nagaraj, and ever, the cost-effectiveness analyses reported below are restricted John 2004).